Molecule library constructed on the basis of backbone structure of microprotein

Abstract

Disclosed is a molecular library comprising a group of a plurality of molecules, wherein each member of the library is a polypeptide having a randomized sequence moiety and a microprotein moiety. The microprotein is a protein comprising an amino acid sequence of 30 or less amino acid residues having the ability to form a particular conformation by spontaneous folding in a solution and is, for example, chignolin comprising the amino acid sequence represented by SEQ ID NO: 1. Also, disclosed is a method for identifying a novel functional molecule using the library of the present invention.

The invention claimed is: 
     
       1. A molecular library comprising a group of a plurality of molecules, wherein each member of the library is a polypeptide having a randomized sequence moiety and a microprotein moiety, and
 wherein each member of the library is a polypeptide molecule comprising the following amino acid sequence:
 -[(Xaa) n -Tyr-Asp-Pro-Xaa-Thr-Gly-Thr-Trp-(Xaa) m ] k - 
 
 wherein Xaa represents an arbitrary amino acid residue, k represents an integer of 2 or larger, each n independently represents an integer of 0 or larger, and each m independently represents an integer of 0 or larger. 
 
     
     
       2. The molecular library according to  claim 1 , wherein each member of the library further comprises a fixed sequence moiety. 
     
     
       3. The library according to  claim 2 , wherein the fixed sequence moiety comprises a whole or partial amino acid sequence of a known polypeptide, or a whole or partial amino acid sequence of a polypeptide selected from the molecular library according to  claim 1 . 
     
     
       4. The molecular library according to  claim 1 , wherein the polypeptide as each member of the library is present in a form associated with a polynucleotide encoding this polypeptide. 
     
     
       5. The molecular library according to  claim 4 , wherein the polypeptide as each member of the library is linked to the polynucleotide encoding this polypeptide. 
     
     
       6. The molecular library according to  claim 4 , wherein the polypeptide as each member of the library is displayed on the surface layer of a bacteriophage, and the polynucleotide encoding this polypeptide is incorporated in the bacteriophage. 
     
     
       7. A polynucleotide library comprising a group of polynucleotides encoding members of the molecular library according to  claim 1 . 
     
     
       8. A method for identifying a polypeptide molecule capable of binding to a target substance, comprising the following steps (a) to (c):
 (a) contacting a library according to  claim 2  with the target substance; 
 (b) selecting a member binding to the target substance from the library; and 
 (c) determining the amino acid sequence of the selected member. 
 
     
     
       9. The method according to  claim 8 , wherein the determination of the amino acid sequence is carried out by the sequencing of the polynucleotide associated with the polypeptide. 
     
     
       10. The method according to  claim 8 , wherein the target substance is a human immunoglobulin.